Elastic MCP Server

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the tool executes queries for data analysis but omits critical details such as required permissions, potential impacts on system performance, rate limits, error handling, or what the response entails (e.g., format options beyond the 'format' parameter). This is a significant gap for a query execution tool.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is highly concise and well-structured in two sentences: the first states the tool's purpose, and the second explains ES|QL. Every sentence adds value without redundancy, making it front-loaded and efficient for quick understanding.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's complexity (executing queries for data analysis), lack of annotations, and no output schema, the description is incomplete. It fails to address behavioral aspects like security, performance, or response handling, which are crucial for effective use. The high schema coverage doesn't compensate for these missing contextual elements.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema has 100% description coverage, with clear documentation for both parameters ('query' and 'format'). The description adds minimal value beyond the schema by mentioning ES|QL's purpose but doesn't elaborate on parameter usage, syntax examples, or format options. This meets the baseline for high schema coverage.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose: 'Execute an ES|QL query for data analysis' with the specific verb 'execute' and resource 'ES|QL query'. It distinguishes ES|QL as 'a piped query language for filtering, transforming, and aggregating data', which helps differentiate it from other query tools like 'search' or 'msearch' in the sibling list. However, it doesn't explicitly contrast with these siblings, keeping it from a perfect score.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides no explicit guidance on when to use this tool versus alternatives. It mentions ES|QL's capabilities (filtering, transforming, aggregating) but doesn't specify scenarios where it's preferred over other query tools like 'search' or 'msearch', nor does it outline prerequisites or exclusions. This lack of comparative context leaves usage unclear.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.